Sidewise propulsion system for ships



Nov. 8, 1966 KOICHI suemo 3,283,735

SIDEWISE PROPULSION SYSTEM FOR SHIPS Filed Nov. 24, 1964 United States Patent Oliice 3,283,735 Patented Nov. 8, 1966 This invention relates to means for sidewise abeam) propulsion of water craft and more particularly to a new and improved side propulsion system for ships having highly advantageous features.

Most of the sidewise propulsion systems for ships known heretofore have been of the type wherein sea water is drawn in from a part of the ship such as its side and then discharged in the 'abeam direction toward either starboard or port, the propulsion system used for this purpose being a system having a special propeller and prime mover for this purpose or a system utilizing at least one cargo oil pump and its prime mover doubly for this purpose.

However, the former system is uneconomical in view of the infrequency of its use, and the latter system is accompanied by problems such :as pump efficiency and pollution of sea water as will be described hereinafter. Accordingly, these systems are considered to be disadvantageous and inconvenient in practical use.

It is an object of the present invention to provide a sidewise propulsion system [for ships wherein the prime mover for driving a cargo oil pump is utilized to drive at least one separately provided pump for sidewise propulsion. It is an ultimate object to lower installation cost and to increase efficiency.

According to the present invention, briefly stated, there are provided, in a water craft provided with a cargo oil pipe system and cargo oil pumps each being driven by a prime mover, :a sidewise propulsion system for said craft comprising atleast one sidewise propulsion pump, coupling means to couple and uncouple readily said sidewise propulsion pump to and from one of said .prime movers, and a water transfer pipe system provided separately from said cargo oil pipe system and having water intake port or ports and .at least one discharge nozzle on each hull side of said craft, whereby water drawn in through the intake port or ports by the sidewise propulsion pump or pumps can be discharged through said discharge nozzle toward one hull side, thereby to propel the craft in the opposite direction.

The nature and details of the invention will be more clearly apparent from the following description with respect of .a preferred embodiment of the invention, when read in conjunction with the accompanying drawing in which like parts are designated by like reference numerals, in which:

FIGURE 1 is a schematic layout diagram indicating the general arrangement of parts of the embodiment; and

FIGURE 2 is a simplified plan view showing one example of a unit of the system shown in FIGURE 1.

Referring to the drawing, reference character P designates a main pump room of a ship S in which a room P and cargo oil pumps 6 are installed. Each pump 6 is driven, through a mechanism consisting of parts such as a drive shaft and speed-reduction gears, by a prime mover 1 installed in an engine room E. Pumps for sidewise propulsion are arranged as shown and adapted to be driven by respective prime movers 1 through a drive change mechanism including change gears 2 and 3 and couplings 4 and 4a.

When a cargo oil pump 6 is to be driven, the corresponding coupling 4a is uncoupled,z-and the coupling 4 is coupled, whereby the sidewise propulsion pump 5 and the prime mover 1 are mutually disconnected. When sidewise propulsion is necessary, the coupling 4 is dis connected and the coupling 4a is connected, whereby the sidewise propulsion pump 5 is driven in a simple manner by the prime mover 1.

Accordingly, the required sidewise propulsion can be imparted to the ship hull by drawing sea water by means of the pump or pumps 5 through the sea water intake port or ports 7 provided on the hull sides and ejecting the sea water through a sea water pipe 8 and from nozzle 9 or 9a provided on the hull outer surface below the water level corresponding to the ballast condition of the ship toward the starboard side or the port side.

In general, the thrust T produced by ejection may be expressed by the following equation.

where:

m is the mass of the ejected water; V is the velocity of the ejected water; and V is the velocity of the ship due to the thrust T.

Furthermore, the propulsion device efliciency 1 in this case may be expressed by the following equation.

This indicate that for high efiiciency, it is. preferable to eject a large quantity of water at a low ejection velocity. Therefore, for the sidewise propulsion system, the use of pumps with a large delivery and relatively low head is advantageous. Since cargo oil pumps, in general, are designed for high heads relative to their capacities, they are not satisfactory for sidewise propulsion systems from the viewpoint of efiiciency. Furthermore, when cargo oil pumps are used doubly for sidewise propulsion, it is necessary to provide separately suitable equipment and device so as to prevent oil remaining in the cargo oil pumps and in the cargo oil pipeline after pumping cargo oil from being discharged into and pollute the sea water in places such as harbours. In contrast, the present invention provides an optimum piping system for a side wise propulsion system which is completely separate from the cargo oil system. Accordingly, the system of this invention is free of the above described disadvantage and inconvenience.

In order to indicate more fully, in specific terms, the utility of the present invention, particularly with respect to its economic aspect, the following calculated comparative data are presented. The known systems selected for comparison are of the types briefly described hereinbelow.

System 1: This system comprises essentially a tunnel disposed transversely across the ship hull with an axial flow, crew propeller suspended therein and is capable of carrying out a reverse operation.

System 2: This system also comprises essentially a tunnel disposed transversely across the ship hull with an axial-flow, screw propeller provided therein. The details of the construction are unavailable.

System 3: This system has been disclosed in Japanese Patent No. 280,654 and comprises essentially a tunnel disposed transversely across the ship hull with an axialflow screw propeller inserted therein. The propeller blades are of variable pitch and reversible pitch type.

A comparison of calculated equipment costs for one metric ton of thrust is as follows:

SYSTEM:

Equipment cost per 1 ton thrust (percent) System of this invention 100 System 1 148.4 System 2 162.7 System 3 265.3

A substantial saving in tugboat costs can be made through the use of the system according to the invention. That is, the number of tugboats used for each docking, emb a rkment or passage of narrow channel can be reduced by at least one tugboat. As one example, a 70,000-ton tanker requires four tugboats each being of approximately 1,500 to 2,000 hp. The cost of using one tugboat of this power is approximately US. $70 per hour at present in Japan. If it is assumed that each docking or embarkment procedure requires 4 hours, each call at a port will result in a saving of 2 $70 4=$560. If it is further assumed that the tanker makes voyages per year, a saving of $560 10 2=$11,200 can be made in a year according to the above calculation.

As is known, the water horsepower (metric) w.h.p. of a pump may be expressed by the following equation.

where: Q is the pump delivery in m. /min.; H is the total head in m.; and r is the pumped liquid density in kg./m. Therefore, according to this invention, pumps producing a required thrust and having high efliciencies adapted to optimum deliveries and heads for sidewise propulsion can be readily selected with required driving power which is not in excess of those of corresponding cargo oil pumps. Accordingly, the invention provides a side wise propulsion system which is superior in both performance and economy to those known heretofore.

It is diflicult to equip the abovementioned conventional Systems 1, 2 and 3, from the constructional point of View, at the stern provided with a shaft tunnel or tunnels, but the system according to the present invention can be easily equipped at the stern.

It will be obvious to those skilled in the art that the present invention can be practiced in a large number of various Ways other than that illustrated above.

Accordingly, it should be understood that the foregoing disclosure relates to only one preferred embodiment of the invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of'the invention as set forth in the appended claim.

What I claim is:

In a cargo-handling vessel, in combination, a cargo oil system having fluid-conveying ducts for handling liquid oil cargo in the vessel and comprising a first pump, a prime mover for driving said first pump, a fluid propulsion system for propelling said vessel sidewise comprising a second pump for pumping water in said propulsion system for propulsion and maneuvering of said vessel, said second pump having a large delivery and low total head the combination of which is so selected that the power required to drive said second pump is not in excess of the power required to drive said first pump, means to selectively and alternately connect said prime mover to said first pump to handle said liquid oil cargo and to said second pump to propel and maneuver said vessel, said vessel comprising a hull having an intake and a discharge port on both sides of said hull, conduit means providing communication between said second pump and the ports to take in water from one side of the hull and discharge it at an opposite side of the hull to propel the vessel sidewise, said cargo oil system and said propulsion system being free of interconnections and thereby independent of each other.

References Cited by the Examiner UNITED STATES PATENTS 896,613 8/1908 Behrman 11416.3

943,604 12/1909 Montjustin 114-163 2,330,674 9/1943 Briggs 114151 2,702,516 2/1955 Tinker 11516 3,043,224 7/ 1962 Brown 103--23 FERGUS S. MIDDLETON, Primary Examiner.

ANDREW H. FARRELL, Examiner.

MILTON BUCHLER, Assistant Examiner, 

